1. Field of the Invention
This invention relates to a data transfer apparatus and method and a data transfer system and medium and, more particularly, to a data transfer apparatus and method in a system in which a plurality of devices are connected by a serial bus, and a data transfer system and medium.
2. Description of the Related Art
Multifunctional image processing devices have remarkably been developed along with recent digital copying machines and copying machine systems. Composite functions are being advanced such that the copying machine is integrated with a facsimile function and connected to a network to add a printer function.
FIG. 2 shows an example of the configuration of an office network including a conventional digital copying machine. In FIG. 2, reference numeral 200 denotes a network such as an Ethernet to which network devices such as an office personal computer, printer and digital copying machine are connected; 201, a personal computer (to be referred to as a PC hereinafter) serving as a server connected to the scanner of a digital copying machine 202; 202, a digital copying machine; 203, a controller for connecting the digital copying machine to the network; 204, a color copying machine; 205, a controller for connecting the color copying machine 204 to the network; 206 and 207, network printers; and 208, 209, 210, 211, 212 and 213, PC clients connected to the network 200.
To perform printout on the PC client side in this network environment, printout data is sent after the client selects the network printer 206 or 207, the digital copying machine 202 via the controller 203, or the color copying machine 204 via the controller 205. If the processing speed of the digital copying machine 202 is insufficient for obtaining a large number of copies by the digital copying machine, printout data can be output to the network printers 206 and 207 via the network 200.
In the conventional network system, however, a large amount of data flows through the network in addition to printout data. Particularly when a large amount of image data or the like flows, the throughput of the whole network greatly decreases.
Even if a job of a specific user or printer is to be preferentially done, this control is difficult to perform on a network involving in many communications, resulting in low job throughput for the preferential device.